Challenge type

steg

Description

Working hard to hide flags…

social_monkeys.jpg

Challenge solve

The first step in solving the challenge is running exiftool on the image. Exiftool is a handy tool for viewing the metadata of an image. It can also be used for writing metadata.

$> exiftool social_monkeys.jpg
ExifTool Version Number         : 11.11
File Name                       : social_monkeys.jpg
Directory                       : .
File Size                       : 3.9 MB
File Modification Date/Time     : 2019:03:25 14:11:19+00:00
File Access Date/Time           : 2019:03:25 14:11:19+00:00
File Inode Change Date/Time     : 2019:03:25 14:11:19+00:00
File Permissions                : rw-r--r--
File Type                       : JPEG
File Type Extension             : jpg
MIME Type                       : image/jpeg
Exif Byte Order                 : Little-endian (Intel, II)
Make                            : Google
Camera Model Name               : Pixel 2
Orientation                     : Horizontal (normal)
X Resolution                    : 72
Y Resolution                    : 72
Resolution Unit                 : inches
Software                        : HDR+ 1.0.220943774z
Modify Date                     : 2019:03:13 16:50:51
Y Cb Cr Positioning             : Centered
Copyright                       : 9pgoYQoPBDWtbbquB4RCYmoX9BXq9XRKeGb8x
Exposure Time                   : 1/111
F Number                        : 1.8
Exposure Program                : Program AE
ISO                             : 129
Exif Version                    : 0220
Date/Time Original              : 2019:03:13 16:50:51
Create Date                     : 2019:03:13 16:50:51
Components Configuration        : Y, Cb, Cr, -
Shutter Speed Value             : 1/111
Aperture Value                  : 1.8
Brightness Value                : 3.13
Exposure Compensation           : 0
Max Aperture Value              : 1.8
Subject Distance                : 1.056 m
Metering Mode                   : Center-weighted average
Flash                           : Off, Did not fire
Focal Length                    : 4.4 mm
Warning                         : [minor] Unrecognized MakerNotes
Sub Sec Time                    : 163442
Sub Sec Time Original           : 163442
Sub Sec Time Digitized          : 163442
Flashpix Version                : 0100
Color Space                     : sRGB
Exif Image Width                : 4032
Exif Image Height               : 3024
Interoperability Index          : R98 - DCF basic file (sRGB)
Interoperability Version        : 0100
Sensing Method                  : One-chip color area
Scene Type                      : Directly photographed
Custom Rendered                 : Custom
Exposure Mode                   : Auto
White Balance                   : Auto
Digital Zoom Ratio              : 0
Focal Length In 35mm Format     : 27 mm
Scene Capture Type              : Standard
Contrast                        : Normal
Saturation                      : Normal
Sharpness                       : Normal
Subject Distance Range          : Close
Compression                     : JPEG (old-style)
Thumbnail Offset                : 26754
Thumbnail Length                : 8868
JFIF Version                    : 1.02
Image Width                     : 4032
Image Height                    : 3024
Encoding Process                : Baseline DCT, Huffman coding
Bits Per Sample                 : 8
Color Components                : 3
Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
Aperture                        : 1.8
Image Size                      : 4032x3024
Megapixels                      : 12.2
Scale Factor To 35 mm Equivalent: 6.1
Shutter Speed                   : 1/111
Create Date                     : 2019:03:13 16:50:51.163442
Date/Time Original              : 2019:03:13 16:50:51.163442
Modify Date                     : 2019:03:13 16:50:51.163442
Thumbnail Image                 : (Binary data 8868 bytes, use -b option to extract)
Circle Of Confusion             : 0.005 mm
Depth Of Field                  : 1.29 m (0.72 - 2.01 m)
Field Of View                   : 67.4 deg
Focal Length                    : 4.4 mm (35 mm equivalent: 27.0 mm)
Hyperfocal Distance             : 2.22 m
Light Value                     : 8.1

This reveals an odd value in the Copyright field: 9pgoYQoPBDWtbbquB4RCYmoX9BXq9XRKeGb8x.

Using CyberChef, we can try to guess what encoding could have been used to create the string. Or we can use the Magic function in CyberChef, which will try to guess the encoding for us.

Magic correctly detects that the string is base58 encoded, and shows us the decoded string:

AFN0M{h4rd_4t_w0rk_m0nk3y2}


Other useful resources: